Fix kotlin annotation processing after java_plugin

I37c1e80eba71ae2d6a06199fb102194a51994989 broke kotlin annotation
processing with a typo in the processors flag to kapt and by
passing -processor to javac with an empty processorpath.

Bug: 77284273
Bug: 122251693
Test: kotlin_test.go
Test: m checkbuild
Change-Id: I17c45d5b3f9df089231af5d2930646ad0e6bf9be
diff --git a/java/kotlin.go b/java/kotlin.go
index 1b2e642..9c47f98 100644
--- a/java/kotlin.go
+++ b/java/kotlin.go
@@ -121,7 +121,7 @@
 
 	kaptProcessor := ""
 	if flags.processor != "" {
-		kaptProcessor = "-P plugin:org.jetbrains.kotlin.kapt3:processor=" + flags.processor
+		kaptProcessor = "-P plugin:org.jetbrains.kotlin.kapt3:processors=" + flags.processor
 	}
 
 	encodedJavacFlags := kaptEncodeFlags([][2]string{